Warm & Humid Weather, and maybe a Thunderstorm

August 24, 2011

A quick check-in this afternoon. 

Today is the 5th day with above average temperatures here in Portland; it’s the first time we’ve had 5 consecutive warmer than average days since early March!  It shows how unusually cool spring and the first half of summer was.  The payoff has been the last 10 days as we’ve made quite a turnaround into typical summer conditions.    In fact this morning’s and yesterday morning’s lows (64 & 65 degrees)  were the warmest of the summer, due to quite a bit of moisture in the air.  It sure hasn’t been extremely humid even for us, but the air definitely has a “heavier” feel to it.

I see thunderstorms firing up over the Cascades and even some lightning strikes well offshore late this morning and into the afternoon.  We sure have the warm and humid conditions that make it “feel thundery”.   There is a very obvious upper level disturbance near Brookings at this hour, and it’s headed right up through Northern Oregon and into Washington overnight.  With nice lifting, lots of moisture to work with, and a warm airmass (no cool marine air to stabilize things), this CAN be a great setup for an overnight thunderstorms.  The curious thing is…none of the mesoscale models show anything to “write home about” the next 24 hours.  Generally they do quite well with this pattern, although a similar setup on Monday, July 25th gave us the surprise morning thunderstorms.  I would prefer to see a more southerly to southeasterly flow to give us nocturnal thunderstorms as opposed to the current south-southwest direction, but those late July storms came out of the southwest as the disturbance moved overhead.

So it boils down to “we MIGHT see a thunderstorm during the next 14 hours, but don’t get your hopes too high”.  That’s for west of the Cascades.  In the Cascades and eastside it’s a far more impressive pattern.  The latest mesoscale discussion from the Storm Prediction Center says “FAST MOVING MULTICELLS…AND PERHAPS A FEW SUPERCELLS…ARE EXPECTED ACROSS ERN/CNTRL ORE AND FAR SRN WA THROUGH THE REMAINDER OF THE AFTERNOON INTO EARLY NIGHT. ISOLATED DAMAGING WIND GUSTS AND LARGE HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS. GIVEN THE LOW POTENTIAL FOR WIDESPREAD SVR…A WW WILL PROBABLY NOT BE NEEDED…BUT CONDITIONS WILL CONTINUE TO BE MONITORED.”

Hopefully we will see some excitement west side tonight since I’m not working this week and I can relax/enjoy from home like everyone else!  Otherwise enjoy the “sultry summer weather” since we’ll be back to the usual programming (clouds and cool) in no time at all I’m sure…September is only 1 week away.

Chief Meteorologist Mark Nelsen